Not applicable.
Not applicable.
The present invention generally relates to the field of disk drives and, more particularly, to damping vibrations in a at least one load beam or suspension which extends toward a computer-readable storage medium disk and which carries a transducer or head to read and/or write information from/to such disk.
Vibrations are an area of concern in disk drive designs, particularly in relation to portable computers. One type of damping system which has been employed in previous disk drive designs is illustrated in FIG. 1 which, as noted thereon, is admitted to be prior art. The disk drive 2 of FIG. 1 includes a disk 6 which has a plurality of concentric tracks (not shown) for storing information thereon and which rotates about an axis 8 at typically high speeds. Information is stored onto and read from the disk 6 by a read/write assembly 12. Components of the read/write assembly 12 include a rigid actuator arm 14 which extends from a location beyond a perimeter 10 of the disk 6 to a location xe2x80x9coverxe2x80x9d the disk or toward but not typically to the rotational axis 8 of the disk 6 (i.e., a reference ray extend perpendicularly from the disk 6 will intersect the actuator arm 14), a flexible suspension or load beam 18 which is fixedly attached to the actuator arm 14 in cantilevered fashion and disposed in opposing relation to one of the two primary data storage surfaces of the disk 6, and a transducer or head 22 which is attached to the load beam 18 and which interfaces with the disk 6 to read and/or write information from/to the disk 6 in a manner known in the art (e.g., by rotational motion of the actuator arm 14 by a voice coil motor to vary the position of the head 22 relative to the disk 6 during rotation of the disk 6). Common practice is for the head 22 to be mounted on the load beam 18 via a slider, gimbled connection, or the like (not shown).
Some disk drive designs which employ a gimbled connection of the head 22 to the load beam 18 have experienced problems with vibrations in this region. The disk drive 2 includes what is commonly referred to as a constrained layer damper 26 to provide sheer damping capabilities or damping of vibrations which are directed generally parallel with the surface of the disk 6 in relation to such a gimbled interconnection. Components of the constrained layered damper 26 include a metal layer 34 which is interconnected with the load beam 18 by an adhesive layer 30. One shortcoming associated with damping mechanisms of this type is that it increases the manufacturing costs of the disk drive. For instance, it is common to remove the load beam 18 from the clean room to install the constrained layer damper 18, such that the load beam 18 with the constrained layer damper 26 mounted thereon must be re-cleaned before reentering the clean room for continuation of the assembly of the disk drive 2. Labor-intensive operations are also involved with the actual installation of constrained layer dampers 26. One such constrained layer damper 26 is required for each load beam 18 of the disk drive 2 which may include a relatively large number of disks in a stack. All of these factors contribute to the overall cost of the disk drive 2. Another problem with these types of vibration damping systems is that constrained layer dampers 26 really only provide sheer damping capabilities. No significant damping is provided in relation to any motion of the head 22 toward the disk 6 by constrained layer dampers 26. Finally, the constrained layer damper 26 is mounted toward the end of the cantilevered connection of the load beam 18 to the actuator arm 14. This increases the gram-loading of the load beam 18 and thereby the control of the position of the head 22 relative to the disk 6.
The present invention generally relates to damping vibrations in disk drives. A first aspect of the present invention relates to what is commonly referred to as a depopulated disk drive which includes at least two disks which define a computer-readable storage medium system of sorts. Each of the disks is a separate computer-readable storage medium (e.g., magnetic) for the storage of information thereon. These two disks are separated by a space and are typically mounted on a typically vertically disposed spindle for rotation within a typically horizontally disposed plane. Other spindle/disk orientations may be utilized. A pair of load beams or suspensions are disposed within the space between the two noted disks. Each of these load beams has a transducer or head mounted on typically an end portion thereof which projects toward one of the disks. These heads thereby project in at least generally opposite directions. Typical functions provided by the noted heads are to read and/or write information from/to their corresponding disk. Movement of the load beams relative to the disks is provided by a load beam drive assembly (e.g., actuator arm with voice coil) and is used to vary the radial position of the heads relative to their respective disk and access different storage regions of the disks. Linear actuators could also be employed. Notably, a damper is disposed between and more preferably couples the two noted load beams. Again, this first aspect of the present invention is applicable to depopulated drives having more than two disks. In such disk drives, preferably each pair of load beams which is disposed within a common space between two adjacently disposed disks includes a damper of the type presented by this first aspect. Moreover, the load beam associated with the end surface of each of the disks on opposite ends of the disk stack may also include such a load beam damper as well, such as in accordance with the third aspect of the present invention which is addressed below.
Various refinements exist of the features noted in relation to the first aspect of the present invention. Further features may also be incorporated in the subject first aspect as well. These refinements and additional features may exist individually or in any combination. Contact between the head and its corresponding disk usually exists when the disk drive is xe2x80x9coffxe2x80x9d (e.g., when the computer-readable storage medium disks are not spinning). Each of the noted load beams may include a hinge and a spring, or a hinge/spring assembly, which collectively allow their corresponding head to be biased toward their corresponding disk to maintain this type of contact. During rotation of the computer-readable storage medium disks (except possibly at the initial startup where a lift-off mechanism may be employed to displace the heads from their corresponding disk), however, the resulting air cushion of sorts above the rotating disks maintains their corresponding heads a predetermined distance thereabove (xe2x80x9cfly heightxe2x80x9d) by a controlled flexure of the load beam (e.g., about the hinge and based on the biasing forces generated by the spring). As such, the load beams are flexible and also commonly referred to as suspensions. The damper associated with a particular load beam may be a different structure from the load beam""s hinge and spring flexure system of sorts. Moreover, preferably the damper is disposed at a location which is at least generally proximate where the noted load beams interconnect with the load beam drive assembly and which is typically a cantilevered interconnection. In the case where the load beam drive assembly includes a rigid actuator arm or actuator arm block which accommodates a plurality of load beams for simultaneous movement thereof, preferably the damper between the noted pair of load beams also interfaces with the actuator arm through an abutting engagement therewith.
At least a certain amount of bias may be provided by the damper, such as for maintaining the same in a certain positional relationship. This may be affected by having the damper be under compression when disposed between the noted pair of load beams. Biasing forces applied to each of the two load beams by a given damper would thereby be directed toward their corresponding disk. Various foams and the like may be put under compression and thereby are an appropriate structure for the damper of the subject first aspect. Retention of the damper between the noted pair of load beams may be enhanced/provided by compression of the damper between adjacent load beams (e.g., establishing a sufficient frictional interface between the damper and each of the load beams of the noted load beam pair). Other ways of maintaining a fixed positional relationship between the damper and the two load beams of the noted load beam pair may be utilized as well, such as by applying appropriate adhesives and the like, in which case preloading of the damper would not be required. Chemical bonds may be employed between the damper and the load beam drive assembly (e.g., actuator arm or block), while limiting the xe2x80x9cbondxe2x80x9d between the damper and its associated load beams to a frictional interface (with or without preloading). In this case, the damper may be installed on the load beam drive assembly before the load beams are attached to the load beam drive assembly.
Appropriate materials for the damper include without limitation viscoelastic materials, elastomers, foams, springs, martensitic memory effect metal (xe2x80x9cmarmemxe2x80x9d), and the like. There are ways of characterizing the damping function provided by the damper of the subject first aspect other than by material selection. For instance, the damper of the first aspect may be characterized as a structure which dampens even its own vibrations. Yet another way of characterizing the damper of the first aspect is that it may be a structure which converts vibrational energy into heat. Still another way of characterizing the damping capabilities of the damper is that it may have a transmissibility (i.e., a ratio of force transmitted by the damper to the force exerted on the damper) of no more than about 80%. The damper of the subject first aspect may also be characterized as a structure which dampens an amplitude of an oscillatory motion of any one or more of load beams (side to side or parallel to the disks, toward and away from the disks, or both) of the noted load beam pair by least about 20% in comparison to if the damper was removed, but with same oscillatory motion continuing. Finally, the damper may be characterized as one which is structured such that the gram-loading on any of its corresponding load beams is no more than about 0.5 gram force.
Further functionality may be provided by/realized through the noted damper of the subject first aspect. Selection of an appropriate material for the damper may also allow the same to provide a particulate filtering function together with the noted vibration damping function with the same xe2x80x9cstructurexe2x80x9d (e.g., through using a low density foam for the damper which would provide both vibration damping and particulate filtering function because of its porous structure). Laminated structures could also be used by the damper to provide both a damping function and filtering function (e.g., separately attaching a filtering structure to an appropriate damping structure). Modification of the air flow within the disk drive may also be realized by the noted damper. Reductions of the air flow within the disk drive should be realized by the inclusion of the damper, which should further reduce load beam vibrations due to windage. It is possible that the damper could be contoured/shaped so as to direct the air flow within the disk drive, such as by directing an air flow to a separate filter structure within the disk drive as well.
A second aspect of the present invention relates to the assembly of a depopulated disk drive. A first head is attached to a first load beam and a second head is attached to a second load beam. Both of the first and second load beams are attached to an actuator arm or actuator arm block which in turn is mounted on a spindle or other appropriate pivot member. When fully assembled, the heads on the load beams are disposed in a space between a pair of adjacently disposed disks. Damping of load beam vibrations is provided by mounting a damper between the first and second load beams which also preferably couples these load beams. Although this damper may be disposed between the first and second load beams after being attached to the actuator arm, preferably the damper is mounted on the actuator arm prior to the attachment of the load beams to the actuator arm.
A third aspect of the present invention is embodied in a disk drive which includes at least one disk of a computer-readable storage medium, which will hereafter be referred to as a xe2x80x9cfirst disk.xe2x80x9d There is also a first suspension or load beam with a first head secured thereto to provide read, write, or read and write functions in relation to the first disk. The first load beam also includes a first hinge/spring assembly principally to bias the first head toward the first disk in a predetermined manner. Movement of the first load beam relative to the first disk, and thereby the first head attached thereto, allows the first head to access different data storage regions of the first disk. A damper interfaces with both the first load beam and its drive mechanism to provide principally a vibrational damping function for the first load beam.
Various refinements exist of the features noted in relation to the third aspect of the present invention. Further features may also be incorporated in the subject third aspect as well. These refinements and additional features may exist individually or in any combination. For instance, the damper and the first hinge/spring assembly may be disposed at displaced locations which further emphasizes that such are in fact different/separate structures. The drive assembly for the first load beam may include an actuator arm having a first actuator arm tip which is defined by a notch. The first load beam may be attached to and/or interface with the actuator arm distally of this notch (i.e., in a direction which is at least generally away from the disk) and pass over the first actuator arm tip toward the first disk. The space between the overlying portions of the first actuator arm tip and the first load beam may be occupied by the damper. The characteristics of the damper presented in relation to the first aspect of the present invention may be utilized in this third aspect of the present invention as well.